A 13-year-old boy selling cookies was left starstruck when he realised the stranger he approached was actually the voice of TV character Bart Simpson.

In a heartwarming video, a teen known only as James, is seen selling boxes of cookies for a school fundraiser outside of a shopping plaza, reports The Daily Mail.

The boy unwittingly approaches voice artist Nancy Cartwright and tells the actress he needs to sell a total of seven boxes.

"Let me guess, you're like, 14?" Cartwright asks James, who then replies that he is 13 years old.

The moment James realises he's meeting the voice of Bart Simpson, Nancy Cartwright.
The moment James realises he's meeting the voice of Bart Simpson, Nancy Cartwright.

Cartwright then switches on her television character voice and introduces herself.

"I'm 10. I'm 10 and I go to Springfield Elementary," she says as the confused teen laughs nervously.

"I'm Bart Simpson, put her there, man," she continues while offering a fist-bump to the boy.

But the joke clearly goes over James' head as he politely replies: "That's a really good impression."

Cartwright giggles and continues to press the eighth-grade student.

"Is it pretty good? Do you know the guy that does it? Do you know who the voice is on that show?" she asks.

"No, not really," James replies.

Cartwright turns on her Bart voice once more and says: "Well shake my hand."

The boy extends his hand and looks at the star for a moment before finally realising who she is.

"Ohh!" he says as it dawns on him. "Oh my god!"

Cartwright laughs at the teen's adorable reaction calling him "so cute" and the two share a hug.

James is seen standing in disbelief as Cartwright continues on as Bart.

"What's happening man? Hi-five dude," she says.

The real-life Bart Simpson continues the sweet gesture by offering to buy 10 packs of cookies from the boy.

The video later shows Cartwright driving in her car before stopping once more to give the boy an autograph as "proof" that she met the real Bart Simpson.

Cartwright, 59, has been the voice of the popular Simpsons character since 1989.